Try to isolate the problem
-Insert other sim card and observe if theres any changes on the signal
-Toggle your phone network setting mode, from auto mode to 3G only.
if the problem still persist you may hand it directly to Globe store if you acquire it from Globe they will facilitate your warranty.
Hi ghee_ehm in connection to what demerok said, several factors can be consider. You can try to download speed test at the app store to check how much kbps/mbps you are getting on specific area. Your phone seems ok since it can browse. If you have a wifi at home try to connect same with your sis hotpsot and observe. Blackberry is fast at browsing due to data compression on internet sites. I had this problem before and found out that my issue was due to Globe network enhancement.
Move around the city. If your phone performs fine in another area then it is a network or coverage issue.